Method for preparing camptothecin derivatives

ABSTRACT

The present invention relates to a process for preparing camptothecin and camptothecin analogs of Formula (I) from compounds of Formula (II) and to novel intermediates useful in their preparation,wherein R1 to R6 represent various substituents.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. application Ser.No. 09/068,185 filed May 14, 1998 and issued as U.S. Pat. No. 6,143,891;which is a 371 application of PCT/US96/17574 filed Nov. 1, 1996; whichclaims priority to U.S. provisional Application 60/006,138 filed Nov. 2,1995.

FIELD OF THE INVENTION

The present invention relates to a method of preparing camptothecin andcamptothecin analogs employing chemical compounds that are useful asintermediates and to processes for the preparation of the intermediates.

BACKGROUND OF THE INVENTION

Camptothecin is a naturally occurring compound, found in Camptothecaacuminata. Camptothecin and camptothecin analogs have been found to haveanti-leukemic and anti-tumor properties.

Camptothecin and camptothecin analogs can be synthesized using processesdescribed in U.S. Pat. No. 4,894,456 to Wall et al. issued Jan. 16,1990; U.S. Pat. No. 4,399,282 to Miyasaka, et al. issued Aug. 16, 1983;U.S. Pat. No. 4,399,276 to Miyasaka, et al issued Aug. 16, 1983; U.S.Pat. No. 4,943,579 to Vishnuvaijala, et al issued Jul. 24, 1990;European Patent Application 0 321 122 A2 filed by SmithKline BechamCorporation, and published Jun. 21, 1989; U.S. Pat. No. 4,473,692 toMiyasaka, et al. issued Sep. 25, 1984; European Patent application No. 0325 247 A2 filed by Kabushiki Kaisha Yakult Honsh, and published Jul.26, 1989; European Patent application 0 556 585 A2 filed by TakedaChemical Industries, and published Aug. 25, 1993; U.S. Pat. No.4,981,968 to Wall, et al. issued Jan. 1, 1991; U.S. Pat. No. 5,049,668to Wall, et al. issued Sep. 17, 1991; U.S. Pat. No. 5,162,532 to Comins,et al.; issued Nov. 10, 1992; U.S. Pat. No. 5,180,722 to Wall, et al.issued Jan. 19, 1993 and European Patent application 0 540 099 A1,filed. by Glaxo Inc., and published May 5, 1993.

Previous method s used in the preparation of camptothecin andcamptotbecin analogs employ resolutions or chiral auxiliaries to obtainenantiomerically enriched intermediates. A problem with these methods isthat a resolution necessitates discarding half of the racemic materialand a chiral auxiliary requires utilizing stoichiometric amounts of achiral subunit to stereoselectively install the chiral center.

A method which uses a process of catalytic asymmetric induction isdescribed in U.S. patent application Ser. No. 08/237,081 and Fang etal., Journal of Organic Chemistry, 59(21), 6142-6143 (1994). Onepotential problem with such prior methods is that some of the chirallyspecific intermediates themselves may exhibit cell toxicity.Furthermore, the final step of the synthesis described in U.S. patentapplication Ser. No. 08/237,081 requires the use of a palladium catalystwhich must subsequently be removed from the final drug substance bymultiple recrystallizations. The potent cytotoxicity of camptothecin andsome of its analogs requires that stringent safeguards be imposed duringall the later steps of manufacturing to protect production personnel andthe environment. Such safeguards increase the complexity and cost ofmanufacturing and handling camptothecin and its analogs.

An object of the present invention is a method for the preparation ofcamptothecin and its analogs wherein the chirality at the 20 position isnot introduced until the penultimate manufacturing step. This wouldreduce the risk of accidental contamination of the environment andinjury to the production worker, and hence, reduces the need forstringent safeguards, since handling and storage of highly biologicallyactive material is minimized.

SUMMARY OF THE INVENTION

The present invention provides a method of preparing compounds ofFormula (I) which comprises oxidizing compounds of Formula (II)

wherein:

R₁ and R₂, which may be the same or different, are independentlyselected from hydrogen, lower alkyl, (C₃₋₇)cycloalkyl, (C₃₋₇)cycloalkyllower alkyl, lower alkenyl, hydroxy lower alkyl, or alkoxy alkyl, or(—CH₂NR₇R₈), wherein:

i) R₇ and R₈, which may be the same or different, are independentlyselected from hydrogen, lower alkyl, (C₃₋₇) cycloalkyl, (C₃₋₇)cycloalkyl lower alkyl, lower alkenyl, hydroxy lower alkyl, or loweralkoxy lower alkyl; or

ii) R₇ represents hydrogen, lower alkyl, (C₃₋₇)cycloalkyl, (C₃₋₇)cycloalkyl lower alkyl, lower alkenyl, hydroxy lower alkyl, or loweralkoxy lower alkyl, and R₈ represents —COR₉,

 wherein:

R₉ represents hydrogen, lower alkyl, perhalo-lower alkyl,(C₃₋₇)cycloalkyl, (C₃₋₇) cycloalkyl lower alkyl, lower alkenyl, hydroxylower alkyl, lower alkoxy, lower alkoxy lower alkyl; or

iii) R₇ represents hydrogen or lower alkyl; and R₈ representsdiphenyl-methyl or —(CH₂)_(t)Ar

 wherein:

t is 0 to 5 and

Ar represents phenyl, furyl, pyridyl, N-methylpyrrolyl, imidazolyloptionally subsituted with one or more substituents selected fromhydroxy, methyl, halogen, and amino; or

iv) R₇ and R₈ taken together with the linking nitrogen form a staturated3 to 7 atom heterocyclic group of formula (IA)

 wherein:

 Y represents O, S, SO, SO₂, CH₂ or NR₁₀,

 wherein:

R₁₀ represents hydrogen, lower alkyl, perhalo lower alkyl, aryl, arylsubstituted with one or more substituents selected from lower alkyl,lower alkoxy, halogen, nitro, amino, lower alkyl amino, perhalo-loweralkyl, hydroxy lower alkyl, lower alkoxy lower alkyl groups or —COR₁₁,

wherein:

R₁₁ represents hydrogen, lower alkyl, perhalo-lower alkyl, lower alkoxy,aryl, aryl substituted with one or more substituents selected from loweralkyl, perhalo-lower alkyl, hydroxy lower alkyl, lower alkoxy loweralkyl groups; or

R₃ and R₄ are independently selected from hydrogen, lower alkyl,(C₃₋₇)cycloalkyl, (C₃₋₇)cycloalkyl lower alkyl, lower alkenyl, hydroxylower alkyl, or alkoxy alkyl; or

R₃ and R₄ taken together form a saturated 5 to 6 atom heterocyclic groupof formula (IB)

 wherein,

n represents the integer 1 or 2; or

R₃ represents —OCONR₁₂R₁₃,

 wherein,

R₁₂ and R₁₃, which may be the same or different, are independentlyselected from hydrogen, a substituted or unsubstituted alkyl group with1-4 carbon atoms or a substituted or unsubstituted carbocyclic orheterocyclic group, with the proviso that when both R₁₂ and R₁₃ aresubstituted or unsubstituted alkyl groups, they may be combined togetherwith the nitrogen atom, to which they are bonded, to form a heterocyclicring which may be interrupted with —O—, —S— and/or >N—R₁₄ in which R₁₄is hydrogen, a substituted or unsubstituted alkyl group with 1-4 carbonatoms or a substituted or unsubstituted phenyl group, and

R₅ represents hydrogen or alkyl, particularly methyl, and

R₆ represents hydrogen or alkyl, particularly hydrogen, and

pharmaceutically acceptable salts thereof.

The present invention further provides a method of preparing compoundsof Formula (I) which comprises dihydroxylating a compound of Formula(II) and subsequent oxidation to yield a compound of Formula (I).

In addition to a method of preparing compounds of Formula (I) fromcompounds of Formula (II), other aspects of the invention include thecompounds of Formula (II) and various intermediates useful in theformation of compounds of Formula (I) and (II). Other aspects andadvantages of the present invention will become apparent from a reviewof the detailed description below.

DETAILED DESCRIPTION OF THE INVENTION

As used herein, the term “loweralkyl” means, a linear or branched alkylgroup with 1-8, preferably 1-4 carbon atoms, such as, methyl, ethyl,propyl, isopropyl, n-butyl, tert-butyl, hexyl and octyl. This definitionalso applies to a loweralkyl moiety in the loweralkoxy, loweralkylthio,and di(loweralkyl)amino groups. Thus, examples of loweralkoxy groups aremethoxy, ethoxy, propoxy, sec-butoxy, and isohexoxy: examples ofloweralkylthio groups are methylthio, ethylthio, tert-butylthio, andhexylthio, and examples of di(loweralkyl)amino groups are dimethylamino,diethylamino, diisopropylamino, di(n-butyl)amino, and dipentylamino.

The terms “halo” and “halogen” as used herein refer to a substitutentwhich may be fluoro, chloro, bromo, or iodo. The term “triflate” as usedherein refers to trifluorometbanesulfonate. The designation “C.” as usedherein means centigrade. The term “ambient temperature” as used hereinmeans from about 20° C. to about 30° C.

Compounds of the present invention may have 1 or more asymmetric carbonatoms that form enantiomeric arrangements, i.e., “R” and “S”configurations. The present invention includes all enantiomeric formsand any combinations of these forms. For simplicity, where no specificconfiguration is depicted in the structural formulas, it is to beunderstood that both enantiomeric forms and mixtures thereof arerepresented. Unless noted otherwise, the nomenclature convention, “(R)”and “(S)” denote essentially optically pure R and S enantiomers,respectively.

Also included in the present invention are other forms of the compoundsincluding: solvates, hydrates, various polymorphs and the like.

Acceptable salts include, but are not limited to, salts with inorganicacids and bases such as hydrochloride, sulfate, phosphate, diphosphate,hydrobromide and nitrate or salts with organic acids such as acetate,malate, maleate, fumarate, tartrate, succinate, citrate, lactate,methanesulfonate, p-toluenesulfonate, palmoate, salicylate, oxalic andstearate. For further examples of acceptable salts see, “PharmaceuticalSalts,” J. Phann. Sci., 66(1), 1 (1977).

One aspect of the present invention provides a method for preparingcompounds of Formula (III);

which comprises dihydroxylating a compound of Formula (II),

using a catalytic asymmetric dihydroxylation reaction. Typically, thereaction may be carried out in the presence of an osmium catalyst (e.g.,potassium osmate (VI) dihydrate, osmium(III) chloride hydrate or osmiumtetroxide), a chiral tertiary amine catalyst (e.g., derivatives of thecinchona alkaloids such as hydroquinidine 1,4-phthalazinediyl diether),an oxidizing reagent (e.g., potassium ferricyanide(III), hydrogenperoxide, N-methylmorpholine N-oxide, or electricity), and a primaryamide (e.g., methanesulfonamide) under basic conditions (e.g. potassiumcarbonate) in an aqueous mixture containing a polar protic solvent(e.g., t-butanol, i-propanol, or n-propanol). The reaction may b ecarried out at a temperature of between about 0° C. to about 30° C. forabout 12 to about 48 hours. Acceptable variations on these conditionsare described in the literature on related catalytic asymmetricdihydroxylation reactions, e.g., K. B. Sharpless et al., J. Org. Chem.58, 3785-3786 (1993).

Alternatively the compound of Formula II is oxidized to a compound ofFormula III in an achiral dihydroxylation reaction to yield a racemiccis-diol which is then resolved enzymatically to give theenantiomerically enriched compound of Formula III. Descriptions ofachiral dihyroxylations are provided by Larock, Comprehensive OrganicTransformations, 493-496 (1989). The resolution reaction may be carriedout in the presence of an acylating enzyme such as pancreatic lipases,Pseudomonas fluorenscens lipases, C. Cylindracea lipases,Chromobacterium viscosum lipases and Aspergillus niger lipases in thepresence of an acylating agent such as vinyl acetate at a temperature ofbetween about 0° C. to ambient temperature for about 2 to about 48hours. Variations on these conditions will be apparent from A. Klibanov,Asymmetric Transformations Catalyzed by Enzymes in Organic Solvents,Acc. Chem. Res. 23, 114-120 (1990).

Compounds of Formula (II) may be prepared by cyclizing a compound ofFormula (IV),

wherein X represents triflate or halo, particularly chloro-, bromo-, andiodo-.

The compounds of Formula (IV) may be cyclized by an intramolecular Heckreaction. The reaction may be carried out in the presence of a palladiumcatalyst (e.g., palladium(II) acetate) under basic conditions in a polaraprotic solvent (e.g. acetonitrile or N,N-dimethylformamide) or a polarprotic solvent (e.g., n-propanol, i-propanol, or t-butanol). A phasetransfer catalyst such as a tetraalkylammonium halide salt (eg.,tetrabutylammonium chloride, tetrabutylammonium bromide, ortetrabutylammonium iodide) may be included when a polar aprotic solventis used. Preferably, a ligand for the palladium catalyst may also beincluded such as a triphenylphosphine, tri-o-tolylphosphine,tri-m-tolylphosphine, or tri-p-tolylphosphine. The reaction may becarried out in an inert atmosphere, such as under nitrogen or argon gasin a suitable reaction vessel equipped with mechanical stirrer andwater-cooled condenser. The reaction mixture may be heated to atemperature between about 50° to about 110° C. for about 1 to about 48hours. Variations on these conditions are described in the literature onthe Heck reaction, e.g., R. Grigg et al., Tetrahedron 46, 4003-4008(1990).

The compounds of Formula (IV) may be prepared by condensing compounds ofFormula (V) and Formula (VI).

wherein,

X represents triflate or halo particularly chloro-, bromo-, and iodo-and Z represents a suitable leaving group such as chloro-, bromo-, andiodo- or OR₁₅, wherein R₁₅ represents triflate, mesylate, or tosylate,or particularly H.

In the case wherein Z represents hydroxy, the condensation reaction iscarried out in an aprotic solvent, e.g., methylene chloride, in thepresence of a trialkyl- or triarylphosphine, e.g., triphenylphosphine,and a dialkyl azodicarboxylate, e.g., diethyl azodicarboxylate, at atemperature between about 0° C. to about 50° C. for about 0.5 to 4hours. Further variations on the above conditions will be apparent fromthe literature on the Mitsunobu reaction, e.g., O. Mitsunobu, Synthesis,1, (1981).

When Z represents halo, triflate, mesylate, or tosylate, thecondensation reaction is carried out in a polar aprotic solvent such asacetonitrile or N,N-dimethylformamide, or a polar protic solvent such asi-propanol or t-butanol, in the presence of a base, e.g., potassiumt-butoxide, at a temperature between about 25° to about 100° C. forabout 1 to 24 hours to yield compounds of Formula (IV). Variations onthe above conditions are described in U.S. Pat. No. 5,254,690 to Cominset al. issued Oct. 19, 1993 and incorporated herein by reference.

Compounds of Formula (VI) may be prepared from compounds of Formula(VII),

wherein,

R₁₆ represents alkyl, particularly methyl.

The dealkylation reaction may be carried out in a polar aprotic solvent,e.g. acetonitrile, in the presence of a suitable dealkylating reagent,e.g., a trialkylsilyl iodide, at a temperature between about 0° C. and100° C. for about 1-12 hours. The trialkylsilyl iodide may be generatedin situ by combining a trialkylsilyl halide, e.g., trimethylsilylchloride, and an alkali metal iodide, e.g., sodium iodide.

Alternatively the dealkylation reaction may be carried out in a polar,protic solvent, e.g., water or ethanol, in the presence of a strongacid, e.g., hydrochloric acid at a temperature between about 0° C. and100° C. for about 1 to 24 hours to yield the compound of Formula (VI).

The starting materials, the compounds of Formula (V) and Formula (VII),are described in U.S. patent application Ser. No. 08/237,081, Fang etal., Journal of Organic Chemistry, 59(21), 6142-6153 (1994),PCT/US95/05425, and PCT/US95/05427.

The compounds of Formula (III) may be oxidized to yield a compound ofFormula (I).

The oxidation reaction may be carried out in a suitable solvent, e.g.,methylene chloride, in the presence of an oxidizing agent, e.g.,dimethylsulfoxide, an activating reagent, e.g., oxalyl chloride, and abase, e.g., triethylamine, at a temperature between about −78° C. and−20° C. for about 0.1 to about 1 hours to yield a compound of Formula(I). Further variations on these conditions will be apparent from theliterature on activated sulfur-based oxidants, e.g., Mancuso and Swern,Synthesis, 165-185 (1981) and March, J., Advanced Organic Chemistry, 3rdedition, John Wiley & Sons, New York (1985), pp. 1057-1060, 1081-1082.

Thus, progressing compounds of Formula (V) and (VI) to compounds ofFormula (I) through the intermediate compounds of Formula (IV), (II),and (III) is schematically represented by the following scheme:

A further aspect of the invention are the novel compounds of Formula(II), (III), (IV), and (VI).

The compounds of Formula (II), (III), (IV), (V), (VI), and (VII) areuseful as intermediates in the preparation of camptothecin andcamptothecin analogs, e.g. compounds of Formula (I), and those describedin European Patent application 0 540 099 A1, filed by Glaxo Inc., andpublished May 5, 1993 and incorporated herein by reference.

A typical preparation of a camptothecin derivative of Formula (I) usingintermediate compounds of Formula (II), (III), (IV), (V), (VI), and(VII) is exemplified herein.

EXAMPLES

The following examples illustrate various aspects of the presentinvention, but should not be construed as limitations. The symbols,conventions and nomenclature not specifically defined below areconsistent with those used in the contemporary chemical literature, forexample the Journal of the American Chemical Society.

In the examples that follow: “mg” means milligram(s), “M” means molar,“mL” means milliliter(s), “mmol” means millimole(s), “L” means liter(s),“mol” means mole(s), “g” means gram(s), “TLC” means thin layerchromatography, “HPLC” means high pressure liquid chromatography, “mm”means millimole(s), “mp” means melting point, “Mhz” means Megaherz,“¹H-NMR” means proton nuclear magnetic resonance, “Hz” means Hertz, “h”means hour(s) and “n” means normal.

Unless otherwise noted all starting materials were obtained fromcommercial suppliers and used without further purification. Allreactions involving oxygen or moisture-sensitive compounds wereperformed under a dry N₂ atmosphere. All reactions and chromatographyfractions were analyzed by thin-layer chromatography on silica gelplates, visualized with UV light and I₂ stain.

Example 1 4-Ethyl-1H-pyrano[3,4-c]pyridin-8-one (a compound of Formula(VI) wherein R₅ is hydrogen and R₆ is methyl)

A 250-mL one-neck round-bottom flask is charged with4-ethyl-8-methoxy-1H-pyrano[3,4-c]pyridine (10 g, 52.4 mmol), preparedas described in U.S. patent application Ser. No. 08/237,081, Fang etal., Journal of Organic Chemistry, 59(21), 6142-6143 (1994),PCT/US95/05425 and PCT/US95/05427, acetonitrile (100 mL), and sodiumiodide (11.8 g, 79 mmol). This mixture is stirred for about 20 minutesat ambient temperature. To the mixture is added trimethylsilylchloride(10 mL, 79 mmol) causing the immediate formation of a white precipitate.The resulting mixture is heated at reflux for about 2 hours. Thereaction is cooled to ambient temperature. To the cooled reactionmixture is added 50 mL of saturated sodium bicarbonate solution. Themixture is stirred for 1 hour at ambient temperature. The precipitate iscollected by filtration on a buchner funnel. The collected solid isdried in vacuo for about 12 hours at between 25 and 38° C. to provide afirst crop 4-ethyl-1H-pyrano[3,4-c]pyridin-8-one as a slightly tancrystalline solid. The filtrate is concentrated in vacuo and theresulting residue recrystallized from acetonitrilelmethanol to giveadditional 4-ethyl-1H-pyrano[3,4-c]pyridin-8-one as a slightly tancrystalline solid. Characterization data: mp 169-171° C. ¹H NMR (CDCl₃,300 MHz): δ1.11 (t, J=7.4 Hz, 3H), 2.27 (q. J=7.4 Hz, 2H), 5.04 (s, 2H),6.17 (d, J=6.8 Hz, 1H), 6.59 (s, 1H), 7.32 (d, J=6.8 Hz, 1H), 13.16 (bs,1H).

Example 24-Ethyl-7-[7-iodo-9-[(4-methyl-piperazinyl)methyl]-2,3-dihydro-[1,4]dioxino[2,3-g]quinolin-8-ylmethyl]-1H-pyrano[3,4-c]pyridin-8-one(a compound of Formula (IV) wherein R₁ is 4-methylpiperazinyl-methyl,R₂, is hydrogen, R₃ and R₄ together are ethylenedioxy, R₅ is hydrogen,R₆ is methyl, and X is iodo)

To a solution of of 4-ethyl-1H-pyrano[3,4-c]pyridin-8-one (200 mg, 1.13mmol) and[7-iodo-9-[(4-methyl-piperazinyl)methyl]-2,3-dihydro-[1,4]dioxino[2.3-g]quinolin-8-yl]-methanol(514 mg,1.13 mmol), prepared as described in U.S. patent applicationSer. No. 08/237,081, Fang et al., Journal of Organic Chemistry, 59(21),6142-6143(1994), PCT/US95/05425, and PCT/US95/05427, in 4.5 mL ofdichloromethane is added triphenylphosphine (326 mg, 1.24 mmol). Afterbeing stirred at ambient temperature for 3 min, the mixture is cooled to0° C., followed by dropwise addition of diethyl azodicarboxylate (0.20mL, 1.24 mmol). The brown solution is warmed to ambient temperature andstirred for 14 h. The solvent is removed under reduced pressure and theresultant residue is chromatographed on silica gel. Elution with 5-10%methanol in dichloromethane affords4-ethyl-7-[7-iodo-9-[(4-methyl-piperazinyl)methyl]-2,3-dihydro-[1,4]dioxino[2,3-g]quinolin-8-ylmethyl]-1H-pyrano[3,4-c]pyridin-8-oneas a yellow solid. Characterization data: ¹H NMR (200 MHz, CDCl3): δ1.03(t, J=7.4 Hz, 3H), 2.18 (s, 3H), 2.25 (q, J=7.4 Hz, 2H), 2.45 (br. s,4H), 3.80 (s, 2H), 4.39 (s, 4H), 5.18 (s, 2H), 5.45 (s, 2H), 5.94 (d,J=6.8 Hz, 1H), 6.60 (s, 1H), 6.80 (d, J=6.8 Hz, 1H), 7.52 (s, 1H), 7.67(s, 1H).

Example 311H-1,4-Dioxino[2,3-g]pyrano[3′4′:6,7]indolizino[1,2-b]quinoline-12(14H)-one,8-ethyl-2,3-dihydro-15-[(4-methyl-1-piperazinyl)methyl](acompound of Formula (II) wherein R₁ is 4-methylpiperazinyl-methyl, R₂is hydrogen, R₃ and R₄ together are ethylenedioxy, R₅ is hydrogen, andR₆ is methyl)

To a solution of4-ethyl-7-[7-iodo-9-[(4-methylpiperazinyl)methyl]-2,3-dihydro-[1,4]dioxino[2,3-g]quinolin-8-ylmethyl]-1H-pyrano[3,4-c]pyridin-8-one(50.0 mg, 0.0813 mmol) in 4 mL of acetonitrile is successively addedpalladium(II) acetate (0.90 mg, 0.0040 mmol), powdered anhydrouspotassium carbonate (22.4 mg, 0.163 mmol) and triphenylphosphine (10.6mg, 0.0406 mmol) at ambient temperature. The mixture is brought toreflux and stirred for 17 h. The solvent is removed under reducedpressure and the resultant residue is chromatographed on silica gel.Elution with 10% methanol in chloroform yields11H-1,4-Dioxino[2,3-g]pyrano[3′4′:6,7]indolizino[1,2-b]quinoline-12(14H)-one,8-ethyl-2,3-dihydro-15-[(4-methyl-1-piperazinyl)methyl]as a yellow solid: Characterization data: mp 223-225° C. ¹H NMR (300MHz, CDCl3): δ1.22 (t, J=7.4 Hz, 3H), 2.29 (s, 3H), 2.45 (q, J=7.4 Hz,2H), 2.57 (br. s, 4H), 3.94 (s, 2H), 4.44 (s, 4H), 5.20 (s, 2H), 4.83(s, 1H), 5.29 (s, 2H), 6.67 (s, 2H), 7.14 (s, 1H), 7.65 (s, 1H), 7.75(s, 1H).

Example 411H-1,4-Dioxino[2,3-g]pyrano[3′,4′:6,7]indolizino[1,2-b]quinoline-12(8H,14H)-one,8-ethyl-2,3-dihydro-8,9-dihydroxy-15-[(4-methyl-1-piperaziuyl)methyl]-(9R-cis)(a compound of Formula (III) wherein R₁ is 4-methylpiperazinyl-methyl,R₂ is hydrogen, R₃ and R₄ together are ethylenedioxy, R₅ is hydrogen,and R₆ is methyl)

To AD-mix-β (1.26 g), containing the chiral ligand hydroquinidine1,4-phthalazinediyl diether, available from Aldrich Chemical Company,Milwaukee, Wis., in 4 mL of water-tert-butyl alcohol (1:1) is addedmethanesulfonamide (24 mg, 0.260 mmol). The brown mixture is cooled to0° C., followed by addition of11H-1,4-Dioxino[2,3-g]pyrano[3′4′:6,7]indolizino[1,2-b]quinoline-12(14H)-one,8-ethyl-2,3-dihydro-15-[(4-methyl-1-piperazinyl)methyl](126 mg, 0.260 mmol). The mixture is allowed to warm to ambienttemperature and vigorously stirred for 36 h. The mixture is diluted with8 mL of water and quenched with 750 mg of sodium sulfite. After beingstirred for an additional 20 min, the mixture is diluted with 5 mL ofdichloromethane and filtered to give a solid which is dried in highvaccum to provide11H-1,4-Dioxino[2,3-g]pyrano[3′,4′:6,7]indolizino[1,2-b]quinoline-12(8H,14H)-one,8-ethyl-2,3-dihydro-8,9-dihydroxy-15[(4-methyl-1-piperazinyl)methyl]-(9R-cis)as a light yellow solid. ¹H NMR indicates a diastereomeric ratio of83:17. Presumably, the two diastereomers are epimeric in the hemiacetalcarbon. Characterization data (major epimer): mp 255-260° C. withdecomposition. ¹H NMR (300 MH, DMSO-d6): δ0.97 (t, J=7.4 Hz, 3H), 1.74(q, J=7.4 Hz, 2H), 2.06 (s, 3H), 2.29 (br. s, 4H), 3.89 (s, 2H), 4.39(s, 4H), 4.51 (ABq, J_(AB)=39 Hz, Δv=82 Hz, 2H), 4.83 (s, 1H), 4.95 (s,1H), 5.26 (s, 2H), 7.23 (s, 1H), 7.54 (s, 1H), 7.70 (s, 1H).

In order to assess the enantiomeric selectivity of the above process,the major diastereomer above is seperately converted to the (S)— and(R)—O-methylmandelates by the following protocol. A mixture of the abovesolid (10 mg, 0.019 mmol), (S)—O-methylmandelic acid (6.4 mg, 0.038mmol), 1,3-dicyclohexylcarbodiimide (7.9 mg, 0.038 mmol) and a catalyticamount of N,N-dimethylaminopyridine in 2 mL of dichloromethane isstirred at ambient temperature for 2 h. The resulting white suspensionis filtered through a short pad of Celite® and washed with 2 mL ofdichloromethane. The combined filtrate and washings are concentratedunder reduced pressure to yield a crude product as a solid. Analysis onthe integrals of the ¹H NMR spectrum (300 MHz, CDCl₃) indicates adiastereomeric ratio of 93:7. This corresponds to 86% enantiopurity forthe major pentacyclic alcohol. The same ratio is obtained when(R)-mandelates are prepared from the major alcohol. The signals for the(S)— and (R)—O-methylmandelates are complementary to each other. In bothcases, the sharp signal for the proton of the anomeric center is usedfor analysis.

Example 511H-1,4-Dioxino[2,3-g]pyrano[3′,4′:6,7]indolizino[1,2-b]quinoline-9,12(8H,14H)-dione,8-ethyl-2,3-dihydro-8-hydroxy-15-[(4-methyl-1-piperazinyl)methyl]-(S)(a compound of Formula (I) wherein R₁ is 4-methylpiperazinyl-methyl, R₂is hydrogen, R₃ and R₄ together are ethylenedioxy, R₅ is hydrogen, andR₆ is methyl)

A solution of oxalyl chloride (0.14 mL,1.5 mmol) in 8 mL ofdichloromethane is cooled to −78° C., followed by dropwise addition ofdimethyl sulfoxide (0.22 mL, 3.1 mmol). The mixture is stirred for 2min, and then11H-1,4-Dioxino[2,3-g]pyrano[3′,4′:6,7]indolizino[1,2-b]quinoline-12(8H,14H)-one,8-ethyl-2,3-dihydro-8,9-dihydroxy-15-[(4-methyl-1-piperazinyl)methyl]-(9R-cis)(40 mg, 0.077 mmol) is added in dimethyl sulfoxide (2 mL). After beingstirred at −78° C. for 15 min, the mixture is treated with triethylamine(0.85 mL, 6.2 mmol) dropwise. The cooling bath is removed and thestirring is continued for 10 min. After being quenched with 10 mL ofwater, the layers are separated and the aqueous layer is extracted withchloroform three times. The combined organic layers are washed withsaturated aqueous sodium chloride, dried over anhydrous sodium sulfateand concentrated under reduced pressure. The resultant brown residue ischromatographed on silica gel. Elution with 10% methanol in chloroformprovides 26 mg (65% yield) of11H-1,4-Dioxino[2,3-g]pyrano[3′,4′:6,7]indolizino[1,2-b]quinoline-9,12(8H,14H)-dione,8-ethyl-2,3-dihydro-8-hydroxy-15-[(4-methyl-1-piperazinyl)methyl]-(S)as a yellow solid. Characterization data: ¹H NMR (300 MH, CDCl3): δ1.06(t, J=7.4 Hz, 3H), 1.91 (m, 2H), 2.31 (s, 3H), 2.59 (br. s, 4H), 3.80(br. s, 1H), 3.97 (s, 2H), 4.46 (s, 4H), 5.32 (s, 2H), 5.55 (ABq,J_(AB)=8.4 Hz, Δv=90 Hz, 2H), 7.60 (s, 1H), 7.66 (s, 1H), 7.72 (s, 1H).

We claim:
 1. A compound of Formulas (IV) or (VI):

wherein: X is halo; R₁ and R₂, which may be the same or different, areindependently selected from hydrogen, lower alkyl, (C₃₋₇) cycloalkyl,(C₃₋₇)cycloalkyl lower alkyl, lower alkenyl, hydroxy lower alkyl, oralkoxy alkyl, or (—CH₂NR₇R₈), wherein: i) R₇ and R₈, which may be thesame or different, are independently selected from hydrogen, loweralkyl, (C₃₋₇) cycloalkyl, (C₃₋₇) cycloalkyl lower alkyl, lower alkenyl,hydroxy lower alkyl, or lower alkoxy lower alkyl; or ii) R₇ representshydrogen, lower alkyl, (C₃₋₇)cycloalkyl, (C₃₋₇) cycloalkyl lower alkyl,lower alkenyl, hydroxy lower alkyl, or lower alkoxy lower alkyl, and R₈represents —COR₉,  wherein: R₉ represents hydrogen, lower alkyl,perhalo-lower alkyl, (C₃₋₇)cycloalkyl, (C₃₋₇) cycloalkyl lower alkyl,lower alkenyl, hydroxy lower alkyl, lower alkoxy, lower alkoxy loweralkyl; or iii) R₇ represents hydrogen or lower alkyl; and R₈ representsdiphenyl-methyl or —(CH₂)_(t)Ar  wherein: t is 0 to 5 and Ar representsphenyl, furyl, pyridyl, N-methylpyrrolyl, imidazolyl optionallysubstituted with one or more substituents selected from hydroxy, methyl,halogen, and amino; or iv) R₇ and R₈ taken together with the linkingnitrogen form a saturated 3 to 7 atom heterocyclic group of formula (IA)

 wherein:  Y represents O, S, SO, SO₂, CH₂ or NR₁₀,  wherein: R₁₀represents hydrogen, lower alkyl, perhalo lower alkyl, aryl, arylsubstituted with one or more substituents selected from lower alkyl,lower alkoxy, halogen, nitro, amino, lower alkyl amino, perhalo-loweralkyl, hydroxy lower alkyl, lower alkoxy lower alkyl groups or —COR₁₁,wherein: R₁₁ represents hydrogen, lower alkyl, perhalo-lower alkyl,lower alkoxy, aryl, aryl substituted with one or more substituentsselected from lower alkyl, perhalo-lower alkyl, hydroxy lower alkyl,lower alkoxy lower alkyl groups; and R₃ and R₄ are independentlyselected from hydrogen, lower alkyl, (C₃₋₇)cycloalkyl, (C₃₋₇)cycloalkyllower alkyl, lower alkenyl, hydroxy lower alkyl, or alkoxy alkyl; or R₃and R₄ taken together form a saturated 5 to 6 atom heterocyclic group offormula (IB)

 wherein, n represents the integer 1 or 2; and R₅ represents hydrogen orlower alkyl, and R₆ represents hydrogen or lower alkyl, orpharmaceutically acceptable salts thereof.
 2. A compound selected fromthe group consisting of: 4-Ethyl-1H-pyrano[3,4-c]pyridin-8-one; or4-Ethyl-7-[7-iodo-9-[(4-methyl-piperazinyl)methyl]-2,3-dihydro-[1,4]dioxino[2,3-g]quinolin-8-ylmethyl]-1H-pyrano[3,4-c]pyridin-8-one.3. The compound of claim 1, wherein R₁ is (—CH₂NR₇R₈) and R₂ is selectedfrom hydrogen, lower alkyl, (C₃₋₇) cycloalkyl, (C₃₋₇)cycloalkyl loweralkyl, lower alkenyl, hydroxy lower alkyl, or alkoxy alkyl, or(—CH₂NR₇R₈), wherein: i) R₇ and R₈, which may be the same or different,are independently selected from hydrogen, lower alkyl, (C₃₋₇)cycloalkyl, (C₃₋₇) cycloalkyl lower alkyl, lower alkenyl, hydroxy loweralkyl, or lower alkoxy lower alkyl; or ii) R₇ represents hydrogen, loweralkyl, (C₃₋₇)cycloalkyl, (C₃₋₇) cycloalkyl lower alkyl, lower alkenyl,hydroxy lower alkyl, or lower alkoxy lower alkyl, and R₈ represents—COR₉,  wherein: R₉ represents hydrogen, lower alkyl, perhalo-loweralkyl, (C₃₋₇)cycloalkyl, (C₃₋₇) cycloalkyl lower alkyl, lower alkenyl,hydroxy lower alkyl, lower alkoxy, lower alkoxy lower alkyl; or iii) R₇represents hydrogen or lower alkyl; and R₈ represents diphenylmethyl or—(CH₂)_(t)Ar  wherein: t is 0 to 5 and Ar represents phenyl, furyl,pyridyl, N-methylpyrrolyl, imidazolyl optionally substituted with one ormore substituents selected from hydroxy, methyl, halogen, and amino; oriv) R₇ and R₈ taken together with the linking nitrogen form a saturated3 to 7 atom heterocyclic group of formula (IA)

 wherein:  Y represents O, S, SO, SO₂, CH₂ or NR₁₀,  wherein: R₁₀represents hydrogen, lower alkyl, perhalo lower alkyl, aryl, arylsubstituted with one or more substituents selected from lower alkyl,lower alkoxy, halogen, nitro, amino, lower alkyl amino, perhalo-loweralkyl, hydroxy lower alkyl, lower alkoxy lower alkyl groups or —COR₁₁,and wherein: R₁₁ represents hydrogen, lower alkyl, perhalo-lower alkyl,lower alkoxy, aryl, aryl substituted with one or more substituentsselected from lower alkyl, perhalo-lower alkyl, hydroxy lower alkyl,lower alkoxy lower alkyl groups.
 4. The compound of claim 3, wherein R₇and R₈ taken together with the linking nitrogen form a saturated 3 to 7atom heterocyclic group of formula (IA)

wherein: Y represents O, S, SO, SO₂, CH₂ or NR₁₀, wherein: R₁₀represents hydrogen, lower alkyl, perhalo lower alkyl, aryl, arylsubstituted with one or more substituents selected from lower alkyl,lower alkoxy, halogen, nitro, amino, lower alkyl amino, perhalo-loweralkyl, hydroxy lower alkyl, lower alkoxy lower alkyl groups or —COR₁₁,and R₁₁ represents hydrogen, lower alkyl, perhalo-lower alkyl, loweralkoxy, aryl, aryl substituted with one or more substituents selectedfrom lower alkyl, perhalo-lower alkyl, hydroxy lower alkyl, lower alkoxylower alkyl groups.